The county has operated under a home-rule charter with five at-large council-members since 1972. Until the 1990s, Delaware County was regarded as a classic suburban Republican county. The Delaware County Republican
political machine was controlled by William McClure and his son
John J. McClure from 1875 to 1965. Delaware County voted for the Republican candidate all but once from 1860 through 1988, with the exception being
Lyndon Johnson's national landslide of
1964. In 1992, however, the county swung from a 21-point win for
George H. W. Bush to a narrow one-point win for
Bill Clinton, who became only the second Democrat to win the county in the 20th century. Clinton won it just under 10 points in 1996, coming up just short of a majority. The county has gone Democratic in every Presidential election since then by 10 points or more by progressively-increasing margins. In the
2004 election Democratic presidential candidate
John Kerry won the county by 14 points.
Barack Obama won it by large 21-point margins in each of his bids for president.
Hillary Clinton carried it by an equally substantial 22 points in 2016.
Joe Biden carried it in 2020 with 62 percent of the vote, his second-strongest performance in Pennsylvania.
Donald Trump turned in the worst showing for a Republican in the county in over 160 years. Driving the county's Democratic shift have been longstanding trends in voter registration advantage and demographics. In 1998, Republicans held a voter registration advantage of about 125,000, but by 2008 that advantage had shrunk to under 20,000 voters. As of the
November 2021 election, Democrats enjoyed a voter registration advantage of 50,000. Propelling and compounding the voter registration shift has been a change in demographics in the county. Since the
2000 Census, the White population of the county has decreased from 80.3% to 68.5% as of the
2020 Census, while, the Black population has risen from 14.5% to 22.7%, driven by the
gentrification of
Philadelphia and
University City neighborhood and rapid demographic shift in
Upper Darby. Further increasing the shift has been the change in education level demographics in the county, as voters have become more college educated and white collar (and, in turn, less blue collar) over the past few decades. While the longstanding Republican registration edge has been erased, Republicans still remain competitive with Democrats at the state and local level. Most Republicans from the county tend to be fiscally conservative and socially moderate, as is the case with Republicans from most suburban Philadelphia counties. In the 2004
US Senate election, Republican
Arlen Specter defeated
Joe Hoeffel but Democrat
Bob Casey, Jr. defeated
Rick Santorum in the 2006 Senate election. All three Democratic state row office candidates carried it in 2008. In 2016, Delaware County elected all Democrats in national office elections except Republican Patrick Meehan (U.S. Representative). After the election of
Donald Trump in
2016, the county rapidly shifted blue as a result of increased Democratic turnout and less enthusiasm from often less conservative suburban Republicans. In the 2019 elections for the Delaware County Council, Democrats swept the board and elected Monica Taylor, Elaine P. Schaefer, and Christine Reuther, gaining control of the county Council for the first time since the
Civil War. This was the first time in history that the county had an all-Democratic Council. As of 2020, all of Delaware County is located in the state's
5th congressional district, represented by Democrat
Mary Gay Scanlon. Prior to 2019, most of Delaware County had been in the
7th congressional district. The district had been held for 20 years by Republican
Curt Weldon until he was ousted by
Joe Sestak, a retired admiral, in the 2006
U.S. House of Representatives election. Also in the 2006 election, Democrat
Bryan Lentz unseated Republican incumbent State Representative
Tom Gannon in the
161st House district. In 2010 Sestak ran for the
senate seat vacated by Arlen Specter and was replaced by Republican
Pat Meehan, who defeated Lentz, the Democratic candidate. Lentz was replaced in the State House by
Joe Hackett, a Republican. Meehan represented the 7th district until his resignation on April 27, 2018. Before it was thrown out by a
Pennsylvania Supreme Court decision in 2018, the 7th Congressional District had been regarded one of the most irregularly drawn districts in the nation.
Voter registration As of May 19, 2025, there are 407,783 registered voters in Delaware County. •
Democratic: 200,307 (49.12%) •
Republican: 145,462 (35.67%) •
Independent: 45,950 (11.27%) •
Third Party: 16,064 (3.94%)
Delaware County Council :
County row officers Row officers, a term unique to Pennsylvania, are a conglomeration of elected officials defined by Article IX, Section 4 of the
Pennsylvania Constitution. This unit of officers includes the position of controller, District Attorney, treasurer, sheriff, register of wills, recorder of deeds,
prothonotaries, clerks of the court, and the coroner. It is thought that this term originated because these positions were arranged in a row on a typical ballot.
United States Senate United States House of Representatives places all of Delaware County in the new
5th congressional district.:
State senate :
State House of Representatives :
Corrections The
George W. Hill Correctional Facility (Delaware County Prison) is located in
Thornbury Township. The jail houses pre-trial inmates and convicted persons who are serving sentences of no longer than two years less one day. ==Education==